The killer systems of S. cerevisiae are defined by the co-infection of two viral agents, an M virus and a helper virus. Each killer toxin is determined by the type of M virus (ScV-M1, ScV-M2, ScV-M28, and ScV-Mlus), which encodes a specific toxin (K1, K2, K28, and Klus). Since their discovery, interest in their potential use as antimicrobial agents has driven research into the mechanisms of action of these toxins on susceptible cells. This review provides an overview of the key aspects of killer toxins, including their origin and the evolutionary implications surrounding the viruses involved in the killer system, as well as their potential applications in the biomedical field and as a biological control strategy. Special attention is given to the mechanisms of action described to date for the various S. cerevisiae killer toxins.

Recently, novel nanobiotechnological approaches have been developed to reduce the impact of pollutants during the synthesis of nanoparticles (NPs). To do so, green synthesis methods have now become widely adopted, using biomolecules to produce high-quality, stable nanoparticles. In this work, we employed the K1 toxin produced by S. cerevisiae as a reducing and capping agent for silver nanoparticles. The synthesis of Ag-K1 NPs was carried out using a concentrated protein fraction from the culture medium of S. cerevisiae 42300 containing the secreted K1 toxin. The obtained nanoparticles were characterized using UV-Vis spectroscopy, STEM, EDS, and FTIR, and the antimicrobial efficacy was determined against S. cerevisiae, P. aeruginosa, and B. subtilis. The synthesized NPs showed high antimicrobial efficacy, killing all tested strains; additionally, dose-response modeling suggested differential activity among the nanoparticles. This work reports, for the first time, the biosynthesis and antimicrobial characterization of silver nanoparticles associated with K1 killer toxin-containing protein fractions.

Recently, novel nanobiotechnological approaches have been developed to reduce the impact of pollutants during the synthesis of nanoparticles (NPs). To do so, green synthesis methods have now become widely adopted, using biomolecules to produce high-quality, stable nanoparticles. In this work, we employed the K1 toxin produced by S. cerevisiae as a reducing and capping agent for silver nanoparticles. The synthesis of Ag-K1 NPs was carried out using a concentrated protein fraction from the culture medium of S. cerevisiae 42300 containing the secreted K1 toxin. The obtained nanoparticles were characterized using UV–Vis spectroscopy, STEM, EDS, and FTIR, and the antimicrobial efficacy was determined against S. cerevisiae, P. aeruginosa, and B. subtilis. The synthesized NPs showed high antimicrobial efficacy, killing all tested strains; additionally, dose–response modeling suggested differential activity among the nanoparticles. This work reports, for the first time, the bio-assisted synthesis and antimicrobial characterization of silver nanoparticles associated with K1 killer toxin-containing protein fractions.